On Thu, Jul 20, 2023 at 06:35:34PM +0800, Hillf Danton wrote: > On Wed, Jul 19, 2023 at 2:16 PM Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote: > > > > I think perhaps the right thing to do is to have handle_userfault() release > > mmap_lock when it returns VM_FAULT_NOPAGE, and to have GUP deal with that > > appropriately? But, some investigation is required to be sure that's okay to do > > in the other non-GUP ways we can end up in handle_userfault(). > > See if making kworker special works. > > --- x/fs/userfaultfd.c > +++ y/fs/userfaultfd.c > @@ -457,6 +457,8 @@ vm_fault_t handle_userfault(struct vm_fa > * close the uffd. > */ > ret = VM_FAULT_NOPAGE; > + if (current->flags & PF_WQ_WORKER) > + ret = VM_FAULT_OOM; > goto out; > } Sorry this won't work - we need userfault to work with all forms of kworkers, especially including kvm async pf. Thanks. -- Peter Xu
